In Vitro Study of the Accuracy of Bone Mineral Measuring Devices in Norway and Sweden

Abstract

Purpose: The aim of the study was to investigate the performance of different types of equipment for bone mineral assessment in Sweden and Norway with standardised phantoms. Material and Methods: Measurements of the bone mineral content of 2 semi-anthropomorphic phantoms, one simulating the human torso and one the lower arm, at 21 hospitals in Norway and Sweden, were undertaken. The phantoms had inserts of hydroxyapatite in different concentrations and were measured together with additions of stearic acid simulating fat. The phantoms were repeatedly measured on 14 dual X-ray absorptiometry, 5 single X-ray absorptiometry, and 3 single photon absorptiometry devices and 1 quantitative CT device. Results: The measurements showed a large spread in the measured hydroxyapatite concentrations among different devices. The inaccuracy was slightly lower than 10% without fat present when the results were expressed as bone mineral areal mass (BMA, g/cm2). With fat included the inaccuracy was at worst 50%. Conclusion: The large inaccuracy found in this study gives rise to a large overlap between healthy and osteoporotic cases and makes the diagnosis of osteoporosis difficult in the individual patient.